There are obviously plenty of battery boxes (and small pres) that run off of a 9v battery, and there are also some that run off of a little 12v battery. What I don't think I've seen, though, is a battery box that uses AA or AAA batteries. Do such battery boxes exist (that would work with the small mics like CA14, AT853, DPA 406x)? If not, why? If so, where are they?